dxf文件格式

python比较详细的文档： https://pythonhosted.org/ezdxf/introduction.html
比较全面的一个库： https://github.com/haplokuon/netDxf

格式化dxf为比较直观的文本

         private void convertFile(String filename)
        {
            StreamReader sr = new StreamReader(filename);
            StreamWriter  sw = new StreamWriter(filename+".txt");
            string code, value;
            StringBuilder text = new StringBuilder();
            String prefix="";
            do
            {
                code = sr.ReadLine().Trim();
                value = sr.ReadLine();
                if (code.Equals("0") || code.Equals("9"))
                {
                    sw.WriteLine(text.ToString());
                    text.Clear();
                    text.Append(prefix);
                    text.Append(value);

                    if (value.Equals("ENDSEC") || value.Equals("ENDTAB") || value.Equals("ENDBLK"))
                    {
                        prefix = prefix.Substring(0, prefix.Length - 1);
                    }
                    else if (value.Equals("SECTION") || value.Equals("TABLE") || value.Equals("BLOCK")
                    {
                        prefix +='	';
                    }
                }
                else if (code.Equals("999"))
                {
                    sw.WriteLine(value);
                }
                else
                {
                    //if(text.Length <50)
                     text.Append("   ").Append(code).Append(':').Append(value);
                }
            } while (value != DxfObjectCode.EndOfFile);
            sr.Close();
            sw.Close();


            //打开文件
            RunCmd("start " + filename + ".txt");

        }

基本内容

SECTION   2:HEADER
	$ACADVER   1:AC1027
	$HANDSEED   5:27F
	ENDSEC
SECTION   2:CLASSES
	ENDSEC
SECTION   2:TABLES
	TABLE   2:VPORT   5:8   330:0   100:AcDbSymbolTable
		VPORT   5:EA   330:8   100:AcDbSymbolTableRecord
		ENDTAB
	TABLE   2:LTYPE   5:5   330:0   100:AcDbSymbolTable
		LTYPE   5:14   330:5   100:AcDbSymbolTableRecord
		ENDTAB
	TABLE   2:LAYER   5:2   102:{ACAD_XDICTIONARY   360:1FF
		LAYER   5:10   102:{ACAD_XDICTIONARY   360:13C   102:}
		ENDTAB
	TABLE   2:STYLE   5:3   330:0   100:AcDbSymbolTable
		STYLE   5:11   330:3   100:AcDbSymbolTableRecord
		ENDTAB
	TABLE   2:VIEW   5:6   330:0   100:AcDbSymbolTable
		ENDTAB
	TABLE   2:UCS   5:7   330:0   100:AcDbSymbolTable
		ENDTAB
	TABLE   2:APPID   5:9   330:0   100:AcDbSymbolTable
		APPID   5:12   330:9   100:AcDbSymbolTableRecord
		ENDTAB
	TABLE   2:DIMSTYLE   5:A   330:0   100:AcDbSymbolTable
		DIMSTYLE   105:27   102:{ACAD_REACTORS   330:255
		ENDTAB
	TABLE   2:BLOCK_RECORD   5:1   330:0   100:AcDbSymbolTable
		BLOCK_RECORD   5:1F   102:{ACAD_XDICTIONARY   360:1CE
		ENDTAB
	ENDSEC
SECTION   2:BLOCKS
	BLOCK   5:258   330:257   100:AcDbEntity   8:0   100:AcDbBlockBegin
		LINE   5:26C   330:257   100:AcDbEntity   8:testLayer
		ENDBLK   5:259   330:257   100:AcDbEntity   8:0   100:AcDbBlockEnd
	ENDSEC
SECTION   2:ENTITIES
	LINE   5:242   330:1F   100:AcDbEntity   8:0   100:AcDbLine
	ENDSEC
SECTION   2:OBJECTS
	DICTIONARY   5:C   330:0   100:AcDbDictionary   281:     1
	ENDSEC
SECTION   2:ACDSDATA   70:     2   71:     6
	ACDSSCHEMA   90:        0   1:AcDb_Thumbnail_Schema
	ENDSEC

最简内容

SECTION   2:HEADER
	$ACADVER   1:AC1027
	$HANDSEED   5:111
	ENDSEC
SECTION   2:CLASSES
	ENDSEC
SECTION   2:TABLES
	TABLE   2:APPID   5:27   330:0   100:AcDbSymbolTable   70:4
		APPID   5:4A   330:27   100:AcDbSymbolTableRecord   100:AcDbRegAppTableRecord   2:ACAD   70:0
		APPID   5:4B   330:27   100:AcDbSymbolTableRecord   100:AcDbRegAppTableRecord   2:AcCmTransparency   70:0
		APPID   5:4C   330:27   100:AcDbSymbolTableRecord   100:AcDbRegAppTableRecord   2:GradientColor1ACI   70:0
		APPID   5:4D   330:27   100:AcDbSymbolTableRecord   100:AcDbRegAppTableRecord   2:GradientColor2ACI   70:0
		ENDTAB
	TABLE   2:VPORT   5:21   330:0   100:AcDbSymbolTable   70:1
		VPORT   5:31   330:21   100:AcDbSymbolTableRecord   100:AcDbViewportTableRecord   2:*Active   70:0   10:0.0   20:0.0   11:21.0   21:21.0   12:0.0   22:0.0   13:0.0   23:0.0   14:0.5   24:0.5   15:10.0   25:10.0   16:0.0   26:0.0   36:1.0   17:0.0   27:0.0   37:0.0   40:2000.0   41:1.9   75:0   76:1
		ENDTAB
	TABLE   2:LTYPE   5:22   330:0   100:AcDbSymbolTable   70:3
		LTYPE   5:32   330:22   100:AcDbSymbolTableRecord   100:AcDbLinetypeTableRecord   70:0   2:ByLayer   3:   72:65   73:0   40:0.0
		LTYPE   5:33   330:22   100:AcDbSymbolTableRecord   100:AcDbLinetypeTableRecord   70:0   2:ByBlock   3:   72:65   73:0   40:0.0
		LTYPE   5:34   330:22   100:AcDbSymbolTableRecord   100:AcDbLinetypeTableRecord   70:0   2:Continuous   3:Solid line   72:65   73:0   40:0.0
		ENDTAB
	TABLE   2:LAYER   5:23   330:0   100:AcDbSymbolTable   70:1
		LAYER   5:35   330:23   100:AcDbSymbolTableRecord   100:AcDbLayerTableRecord   2:0   70:0   62:7   6:Continuous   290:1   370:-3   390:0
		ENDTAB
	TABLE   2:STYLE   5:24   330:0   100:AcDbSymbolTable   70:1
		STYLE   5:36   330:24   100:AcDbSymbolTableRecord   100:AcDbTextStyleTableRecord   2:Standard   3:arial.ttf   70:0   71:0   40:0.0   41:1.0   42:0.0   50:0.0
		ENDTAB
	TABLE   2:DIMSTYLE   5:28   330:0   100:AcDbSymbolTable   70:0   100:AcDbDimStyleTable
		ENDTAB
	TABLE   2:VIEW   5:25   330:0   100:AcDbSymbolTable   70:0
		ENDTAB
	TABLE   2:UCS   5:26   330:0   100:AcDbSymbolTable   70:0
		ENDTAB
	TABLE   2:BLOCK_RECORD   5:29   330:0   100:AcDbSymbolTable   70:2
		BLOCK_RECORD   5:37   330:29   100:AcDbSymbolTableRecord   100:AcDbBlockTableRecord   2:*Model_Space   340:0
		BLOCK_RECORD   5:38   330:29   100:AcDbSymbolTableRecord   100:AcDbBlockTableRecord   2:*Paper_Space   340:0
		ENDTAB
	ENDSEC
SECTION   2:BLOCKS
	BLOCK   5:39   330:37   100:AcDbEntity   8:0   100:AcDbBlockBegin   2:*Model_Space   70:0   10:0.0   20:0.0   30:0.0   3:*Model_Space
		ENDBLK   5:4E   330:37   100:AcDbEntity   8:0   100:AcDbBlockEnd
	BLOCK   5:3A   330:38   100:AcDbEntity   8:0   100:AcDbBlockBegin   2:*Paper_Space   70:0   10:0.0   20:0.0   30:0.0   3:*Paper_Space
		ENDBLK   5:4F   330:38   100:AcDbEntity   8:0   100:AcDbBlockEnd
	ENDSEC
SECTION   2:ENTITIES
	LINE   5:3B   330:37   100:AcDbEntity   8:0   62:0   100:AcDbLine   10:0.0   20:0.0   30:0.0   11:300.0   21:300.0   31:0.0
	LINE   5:3C   330:37   100:AcDbEntity   8:0   62:0   100:AcDbLine   10:0.0   20:300.0   30:0.0   11:300.0   21:0.0   31:0.0
	LWPOLYLINE   5:3D   330:37   100:AcDbEntity   8:0   62:0   100:AcDbPolyline   90:20   70:128   43:0.0   10:0.0   20:0.0   10:20.0   20:20.0   10:20.0   20:0.0   10:40.0   20:20.0   10:40.0   20:0.0   10:60.0   20:20.0   10:60.0   20:0.0   10:80.0   20:20.0   10:80.0   20:0.0   10:100.0   20:20.0   10:100.0   20:0.0   10:120.0   20:20.0   10:120.0   20:0.0   10:140.0   20:20.0   10:140.0   20:0.0   10:160.0   20:20.0   10:160.0   20:0.0   10:180.0   20:20.0   10:180.0   20:0.0   10:200.0   20:20.0
	POLYLINE   5:3E   330:37   100:AcDbEntity   8:0   62:0   100:AcDb3dPolyline   10:0.0   20:0.0   30:0.0   70:16
	VERTEX   5:40   330:3E   100:AcDbEntity   8:0   100:AcDbVertex   100:AcDb3dPolylineVertex   10:0.0   20:0.0   30:0.0   70:64
	VERTEX   5:41   330:3E   100:AcDbEntity   8:0   100:AcDbVertex   100:AcDb3dPolylineVertex   10:0.0   20:0.0   30:100.0   70:64
	VERTEX   5:42   330:3E   100:AcDbEntity   8:0   100:AcDbVertex   100:AcDb3dPolylineVertex   10:-100.0   20:0.0   30:100.0   70:64
	SEQEND   5:3F   330:3E   100:AcDbEntity   8:0
	CIRCLE   5:43   330:37   100:AcDbEntity   8:0   62:0   100:AcDbCircle   10:0.0   20:0.0   30:0.0   40:50.0
	ARC   5:44   330:37   100:AcDbEntity   8:0   62:0   100:AcDbCircle   10:0.0   20:0.0   30:0.0   40:100.0   100:AcDbArc   50:0.0   51:90.0
	ELLIPSE   5:45   330:37   100:AcDbEntity   8:0   62:0   100:AcDbEllipse   10:0.0   20:0.0   30:0.0   11:0.0   21:100.0   31:0.0   40:0.5   41:0.0   42:4.0
	TEXT   5:48   330:37   100:AcDbEntity   8:0   62:0   100:AcDbText   10:300.0   20:0.0   30:0.0   11:300.0   21:0.0   31:0.0   40:30.0   1:aaaa中文00000  50:0.0   72:0   100:AcDbText   73:2
	ENDSEC
SECTION   2:OBJECTS
	DICTIONARY   5:50   330:0   100:AcDbDictionary   280:0   281:1   3:ACAD_GROUP   350:51
	DICTIONARY   5:51   330:50   100:AcDbDictionary   280:0   281:1
	ENDSEC

文件格式

http://www.qcad.org/doc/dxflib/2.5/reference/writing.html
https://www.autodesk.com/techpubs/autocad/dxf/reference/

基本结构

0 //section前导0
SECTION //SECTOIN 标记
2 //SECTION 后续标记2
HEADER //SECTION名称：HEADER CLASSES TABLES BLOCKS ENTITIES OBJECTS THUMBNAILIMAGE
9 //属性前导9
$ACADVER //属性名，版本
1 //属性类型 , 可以多个属性类型、属性值对，直到9开始下一属性，或者0a 0ENDSEC
AC1027 //属性值
9 //新属性
.....
70

组码表

0 T 实体类型，比如：SECTION TABLE CLASS CIRCLE LINE ENDBLK...
2 
1  文本值，比如dim标注		
5  实体句柄，顺序编号的十六进制字符串
6 线样式名
7 文本样式名
8 图层名，默认存在一个名称为0的图层
100 子类标识 Subclass data marker，如AcDbEntity/AcDbPolyline/AcDbCircle/AcDbArc,
330 owner // Soft-pointer handle  to other objects . Translated during INSERT and XREF. 

值

 0 = BYBLOCK, 256 = BYLAYER
 $MEASUREMENT 70 Sets drawing units. 0=English; 1=Metric

明细

https://www.autodesk.com/techpubs/autocad/dxf/reference/
http://docs.autodesk.com/ACD/2011/CHS/filesDXF/WSfacf1429558a55de185c428100849a0ab7-5f35.htm
http://help.autodesk.com/view/OARX/2018/ENU/?guid=GUID-235B22E0-A567-4CF6-92D3-38A2306D73F3
https://www.autodesk.com/techpubs/autocad/acad2000/dxf/